AB PLC5/11 1771-OAD outputs not active

PaulKraemer · Jan 24, 2005

Hi,

A little over a year ago, I set up a control system with an AB PLC 5/11. It was working fine, but the machine has sat idle since then. Now my customer wants to use it, and it appears that none of the 1771-OAD AC (12-120V)output modules are working. Their "Active" lights are not lit. This is true for everone one of these modules that I have installed (there are nine total - seven in the same chassis as the PLC, and two in a second chassis that communicates with the PLC using a 1771-ASB card.

I had my customer use the key on the PLC to switch it to "Program" mode and back to "Run". He has cycled power to the PLC several times as well. I can't imagine that nine of these modules would have all failed. If anyone could suggest anything I can check, I'd really appreciate it.

Thanks,
Paul

Mickey · Jan 24, 2005

Power Supply? Then I might Power down and pull all mudules and reseat.

harryting · Jan 24, 2005

Sit idle for a year? Lost its programming, I bet. If it's a nice location, ask for a round trip ticket

PaulKraemer · Jan 25, 2005

If the PLC has lost its program, I can see why none of the individual output lights would be lit - but shouldn't the Active light still be lit? According to the Installation instructions, the active light should be lit as long as "the rack power supply has properly established 5V dc and the processor is in RUN mode."

Jan650GS · Jan 25, 2005

Hi Paul,

I agree, sounds to me like a lost program.

Does the Run indication LED light up when your customer switch
from STOP to RUN?

Hope u get it going,

Jan

PaulKraemer · Jan 25, 2005

I don't think there is a light called "RUN", but when the key is in the "RUN" position, the "PROC" light turns steady green.

The "Battery" light is lit steady red. Would this indicate that the program has been lost?

But even if the program is lost, shouldn't the Active lights on the output cards still be lit green?

Thanks for your help.
Paul

mgvol · Jan 25, 2005

If the Battery light is red, it's dead and definitley lost its program.

Jan650GS · Jan 25, 2005

Yup,

The "PROC" indicates that the processor is still OK,
but the red battery LED doesnt sound good.

I also think the program is lost.
I think the chance of that is even greater if the PLC was
without power for over a year, the battery ran flat.

Think you should take a new battery with you. I think on the PLC 5's the battery can last up to 5 years, but this is probably an old PLC.

Im realy not sure bout the Active lights.
Think they turn green when the processor "knows" the type of rack and id's the cards are there.
Since all the configuration data will be lost if the power and backup power are removed, I think they will only light up when you download the program again.

At least you know that its not a faulty processor.

Jan.

PaulKraemer · Jan 25, 2005

Just to make sure I am perfectly clear...if the battery is dead and the program is gone, does this explain why the Active lights on my output cards are not lit? Or is that an indication of another problem?

According to the instruction manual on the output card, the Active light should be lit when the rack power supply has properly established 5V dc and the processor is in RUN mode. It doesn't say anything about the processor having a program in it. I'm pretty sure that the output cards have 5 Vdc because the PLC and all of the input cards that I have in the same chassis as the problem output cards are all powered.

mgvol · Jan 25, 2005

Well, let me muddy the water some more; I have a 5/80E processor with 1 output module in it (and the battery is dead). I just cleared the CPU memory, and the output module "Active" light is still lit.

First things first: If the Battery light on your customer's CPU is red, replace the battery and re-load the program. Only then should you try to evaluate this other problem; one problem may cause/mask symptoms of the other.

Jan650GS · Jan 25, 2005

Paul,

I not gonna put my head on a block.
Im not dead sure bout the active lights thing, but im pretty sure that the active light indicates that the processor is addressing the card on the rack.
Since the processor dont even know what size or type of rack its talkin to, I imagine that its cant address the cards.
I dont think there has to be a user program in the PLC, just the configuration data.

Maybe give the guys at Rockwell a quick buzz just to make sure.

Jan.

PaulKraemer · Jan 25, 2005

Ok..it sounds like I have to get a new battery and download the program again. I just have one more question. I am using RsLogix 5 version 5.50. The processor is a PLC 5/11. Looking at my copy of the ladder program (which I'm sure is current but I didn't write it myself), if I go into "IO Configuration", the information shown there doesn't seem to reflect the true IO Configuration. It shows a 1771-A1B 4 slot chassis and has no info about the actual modules in these slots. I actually have two chassis, one with sixteen slots and the other with eight.

I know this program worked before, but I'm surprised to see that the I/O info doesn't appear to be in there. Is this because the I/O config info is not necessary in the offline program, or should I be afraid to download this program without entering the correct I/O configuration?

mmw · Jan 25, 2005

The I/O config info to which you refer is just documentation (for a PLC-5 system) and therefore has nothing to do with what's actually in the chassis or how it works.

Jan650GS · Jan 25, 2005

Paul,

I also agree with mmw, the info is just for documentation.
One thing that can make a difference is the channel configuration.

Your ouput cards that arent working, are they on the remote rack?
Do you use a remote IO adapter? I cant remember if the comms is setup via software or dips.

I think there is a LED on the processor marked "REMOTE". This should be green is the processor has comms with the remote rack.

Ken Moore · Jan 25, 2005

I could be mistaken, but I believe , a PLC-5 does not need the I/O configuration to work / run, I've got a couple in this condition. Discrete input and output words are created in memory, depending on addressing method (1 slot, 2 slot etc..)
Analog is handled by Block Transfer, so not an issue either.

So, if your racks are configured correctly, I wouldn't worry to much.

If you look at the output file, do you have entries for all the discrete output cards?

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Must type faster!

AB PLC5/11 1771-OAD outputs not active

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